The London 2012 Olympic torch will be a three-sided golden cone with the flame burning through its perforated shell.
The prototype, created by east London designers Edward Barber and Jay Osgerby, is being unveiled at St Pancras station.
Made from an aluminium alloy, it is light enough to be carried by young people who are expected to make up half of the 8,000 torchbearers.
The 70-day relay will take in most of the UK ahead of next year's Games.
It will start at Land's End on 19 May and travel 8,000 miles before arriving at the Olympic Stadium on 27 July for the lighting of the cauldron at the opening ceremony.
London 2012 organisers say the torch will come within an hour's travelling time of 95% of the UK population and thousands of people are expected to celebrate along the route, with shows and concerts planned on 66 of the 70 days.